Critical habitat includes the stream channels within the designated stream reaches, and includes a lateral extent as defined by the ordinary high-water line (33 CFR 329.11). In areas where the ordinary high-water line has not been defined, the lateral extent will be defined by the bankfull elevation. Bankfull elevation is the level at which water begins to leave the channel and move into the floodplain and is reached at a discharge which generally has a recurrence interval of 1 to 2 years on the annual flood series. Critical habitat in estuaries is defined by the perimeter of the water body as displayed on standard 1:24,000 scale topographic maps or the elevation of extreme high water, whichever is greater.

See the final rule (70 FR 52488) for descriptions of areas excluded from this critical habitat designation. Economic exclusions were clipped out of the data. Military areas ineligible for designation due to qualifying Integrated Natural Resources Management Plans (INRMPs) and excluded due to national security impacts were not clipped out of the data.